Why did some new crown vaccination sites test positive?


　　Experts say it is not a resurgence of the virus

　　Ask about the new crown vaccine

　　Recently, some provinces have tested positive for the new coronavirus nucleic acid in environmental samples collected by the new crown vaccination unit.

　　Xianyang means "red light", suggesting that there may be a new coronavirus here.

　　So, when the “red light” was turned on during the investigation around the vaccination site this time, does it mean that the virus is resurging?

Will it bring infection?

　　To this end, the Chinese Center for Disease Control and Prevention conducted further research and analysis on samples and vaccine solutions, and issued the "Technical Recommendations on Environmental Specimen Monitoring of New Coronary Vaccination Units" (hereinafter referred to as "Recommendations") on January 24. It is believed that the positive cause is the dead strain in the vaccine solution.

　　So the question is, the virus is dead, why can it show the sun?

How can it prove that it really died?

　　How did it die

　　To prove that the virus is dead, you must first figure out how it died.

　　The new crown vaccine currently being vaccinated is an inactivated vaccine.

As the name suggests, it "kills" the virus.

　　Killing viruses is not using the "knife" and "gun" in the macroscopic world, but using chemical methods to inactivate the vital molecules of the virus.

　　For example, β-propiolactone does not directly act on the protein, but it can go into the virus to destroy its nucleic acid, which is like drinking arsenic on the virus and "stomaching down" to death.

　　For another example, formaldehyde can destroy the amino-containing nucleotide bases (such as A, G, U) in the viral nucleic acid, as well as the coat protein of the virus. This is like pouring sulfuric acid on the virus and "burning the body and mind". dead.

　　There are many kinds of virus inactivating agents.

Yang Xiaoming, Chairman of Sinopharm Group, Zhongsheng Biological, previously mentioned to the Science and Technology Daily reporter of popular science inactivated vaccines, that inactivation alone, Zhongsheng promoted the inactivation of four or five different inactivators at the same time during research and development. Effect research.

Inactivation cannot be enough. If there are live viruses, it will cause infection; but it cannot be "overfired". If inactivation destroys all antigens on the surface of the virus, the effectiveness of the vaccine will be poor.

　　Inactivation is like "cutting the weeds and roots on tofu". You must not crush the tofu, but also root out the grass.

　　Regarding the question of whether it is "dead" and whether it is still effective, the researchers did a lot of experimental verification work during the research and development, and figured out the optimal type of inactivation agent and the appropriate inactivation time, temperature, dosage and other parameters. Before production.

　　It really died

　　After production and before the vaccine arrives at the inoculation unit, it needs to be inspected. One of the basic requirements for qualification is to verify that the virus is indeed dead.

　　my country implements a strict vaccine batch issuance system.

At a press conference held by the Joint Prevention and Control Mechanism of the State Council on December 31, 2020, Chen Shifei, deputy director of the National Medical Products Administration, stated that each batch of new crown vaccines that leave the factory will be issued by the drug regulatory authority.

At present, the drug regulatory and inspection agencies of Beijing and Hubei Province have been granted to undertake the batch issuance of the new crown vaccine.

　　In other words, every vaccine that enters the vaccination process has undergone strict data review and laboratory testing for the same batch of vaccines.

　　A paper entitled "Key Points of Virus Inactivated Vaccine Production Process" written by researchers from the Center for Drug Evaluation of the National Medical Products Administration showed stringent requirements for virus inactivation testing: detailed information on virus inactivation verification is required , Sensitive cells can be used to blindly pass 3 generations, each generation of cells are detected, the most sensitive detection method is used to verify that there is no live virus, the method should have sufficient sensitivity and repeatability, and each sampling point should take double samples... …

　　In summary, the inactivated vaccine must be verified with repeatable and double samples, and ensure that the third generation is not alive. Some verifications need to be supplemented with animal testing to prove the inactivated vaccine from multiple angles and multiple levels. The virus is really dead.

　　As long as "pairing", you can show the sun

　　So, since the virus in the inactivated vaccine is completely dead, why is there a "red light" for nucleic acid testing of environmental samples?

　　The principle of nucleic acid detection can be imagined as two small worms gnawing on willow leaves on both sides. As long as the willow leaves are "tasteful", the small worms will walk back and forth on both sides of the willow leaves, copying the same willow leaf edge pattern every time they go. The same nucleic acid.

　　"Taste" is the key. As long as the "bumps" on the two small bugs and the "bumps" of the willow leaves can match, they can play the role of primers and guide PCR (polymerase chain reaction). A lot of the same sequence is amplified from the nucleic acid sequence of the specific fringe, and then the positive is revealed.

　　If the primer cannot find a "matched" sequence and cannot amplify, it will be negative.

　　In the process of vaccine inactivation, the virus is completely dead, but the "face" of the nucleic acid may not be completely destroyed.

To use an inappropriate analogy, facial recognition of a dead person is likely to succeed.

　　In this regard, the Chinese Center for Disease Control and Prevention stated in the above-mentioned "Recommendations" that it is not recommended to routinely collect environmental specimens and nucleic acid tests for inoculation units.

If surveillance has been carried out and it is found to be positive, or the viral nucleic acid test of environmental samples collected near the vaccination site is positive, it is recommended to use the virus genome sequencing method to determine whether the nucleic acid is a vaccine strain.

In other words, a more comprehensive sequencing method is used to further verify whether the "red light" is a true alarm.